% Credit: https://www.baeldung.com/cs/latex-drawing-graphs

\documentclass{article}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}[node distance={15mm}, thick, main/.style = {draw, circle}]
  \node[main] (1) {$x_1$};
  \node[main] (2) [above right of=1] {$x_2$};
  \node[main] (3) [below right of=1] {$x_3$};
  \node[main] (4) [above right of=3] {$x_4$};
  \node[main] (5) [above right of=4] {$x_5$};
  \node[main] (6) [below right of=4] {$x_6$};
  \draw[->] (1) -- (2);
  \draw[->] (1) -- (3);
  \draw (1) to [out=135,in=90,looseness=1.5] (5);
  \draw (1) to [out=180,in=270,looseness=5] (1);
  \draw (2) -- (4);
  \draw (3) -- (4);
  \draw (5) -- (4);
  \draw[->] (5) to [out=315, in=315, looseness=2.5] (3);
  \draw[->] (6) -- node[midway, above right, sloped, pos=1] {+1} (4);
\end{tikzpicture}
\end{document}
